Agriculture Reference
In-Depth Information
Synonyms —
Amomum zingiber
L.,
Zingiber blancoi
Mask.,
Z. majus
Rumph.,
Curcuma lon-
gifolia
Wall, ll,
Zingiber cholmondeleyi
(F.M. Bailey) K. Schum.,
Zingiber sichuanense
Z.Y. Zhu, S.L.
Zhang & S.X. Chen.
Family —
Zingiberaceae
Common Names —
Ginger, gingembre (Fr.)
African Names —
Arabic: zanjabeel; Hausa: sankanjabir, citaraho; Igbo: jinja; Swahili: tan-
gawizi; Yoruba: ata-Ie, jinja
Description —
Ginger is the rhizome of the tropical plant
Zingiber officinale
Roscoe. Two
varieties are known, the mild-tasting and often peeled West Indian variety called “Jamaican ginger”
and the very pungent and usually unpeeled variety called “Nigerian” or “African ginger.” The plant
is a perennial with green-purple flowers that occur in terminal spikes and resemble orchids. It has a
distinctive odor and aromatic, pungent, and agreeable taste.
Habitat and Distribution —
The natural habitat is the well-drained savanna and semitropics.
The plant is, however, cultivated in nearly all parts of the continent. A variety similar to the West
Indian mild-tasting cultivar has been successfully developed at the Root Crop Research Institute of
Nigeria, Umudike-Umuahia.
Medicinal Uses
—
Ginger is used extensively as a culinary plant and in African folk medicine
as a carminative, diuretic, and antiemetic. In China and Japan, it is one of the most common ingre-
dients in the preparation of remedies for gastrointestinal distress, liver diseases, and hypertension.
Constituents —
Ginger yields 1-3% volatile oil, which consists mainly of camphene, citral,
cineol, linalool, zingiberene, bisbolene, zingiberol, zingibcrenol, and methylheptenone. The plant
also yields pungent phenolic principles known as gingerols and shogaols. The shogaols, which are
more pungent than the gingerols, are believed to be formed by dehydration and the degradation of
the gingerols during drying and extraction.
608,1114
Pharmacological Studies —
The methanolic extracts of the rhizome of ginger showed strong
positive inotropic effects on the guinea pig isolated left atria in a dose-dependent manner. The
cardiotonic properties are associated with the presence of gingerols.
1115
Two of the constituents,
(6)-gingerol and (6)-shogaol, have been shown to be cardiodepressant at low doses and cardiotonic
at high doses.
1116
Both compounds inhibited spontaneous motor activity, produced antipyretic and
analgesic effects, and prolonged hexobarbital-induced sleep in laboratory animals.
The compounds also possess strong antitussive effects that were found comparable to those of
dihydrocodiene.
1117
(6)-Gingerol and (6)-shogaol were also shown to suppress gastric contractions.
It is noteworthy that (6)-shogaol inhibited intestinal motility when administered intravenously but
accentuated gastrointestinal motility after oral administration.
1118
Gingerols and shogaols have been
shown to have demonstrable hypotensive effects.
1119
(6)-Shogaol induced pressor responses in the
blood pressure of rats at a dose of 0.5 mg/kg i.v., which was markedly reduced by spinal destruction
to the sacral cord level (unlike norepinephrine). The pressor response induced by (6)-shogaol was
also reduced by hexamethonium (10 mg/kg i.v.) and phentolamine (10 ng/kg i.v.) and similar agents
when the spinal cord was destroyed to the thoracic cord level, but the pressor response remained
unaffected by these blockers in rats whose spinal cords were destroyed to the sacral cord level.
1120
When (6)-shogaol (0.5 mg/kg i.v.) was administered to rats, blood pressure showed a triphasic
response, which comprised a rapid fall, followed by a rise and a delayed fall. It was also observed
that the rapid fall, which followed immediately after the injection of the compound, disappeared
with the use of atropine and vagotomy, whereas the sequential marked rise was not affected by
α-adrenoceptor blockade and calcium antagonists and ganglion blockade; only a combination of the
three inhibited this pressor response. The repeated injections of (6)-shogaol caused tachyphylaxis in
mesenteric and tail vascular beds and a slight tachyphylaxis in rat hindquarters.
The anti-inflammatory activity of ginger has been evaluated by many investigators.
1121
In several
preclinical studies with experimental animals, ginger and some of its compounds were effective in
preventing chemically induced arthritis.
1122
Ginger has also been evaluated against a rheumatoid
